1+2+3 4-Bit Binary Card Sorter

By Nigel Hall

Purpose: To demonstrate a 4-bit binary sort using a chopstick and 16 3"x5" index cards.

You will need: 16 index cards, chopstick, scissors, holepunch, pen, and ruler.

Punch 4 holes in each card, 1" from the edge and 1" apart along the top of the cards. Make sure your holes line up when you stack the cards.

Number each card from 0 to 15. Write the binary value below each hole, as shown. The values of the holes proceed from 8, at left to 4, 2, and 1, at right.

Now take a pair of scissors and for every punch hole that represents a binary 1, cut it open so the hole becomes a slot. The cards for 0, 5, and 15 are shown below.

Illustration by Mark Frauenfelder

Shuffle the cards. Starting with the right hole moving left, insert chopstick, lift out cards, and place lifted cards in front of pack. Repeat until done with left hole farthest left.

Cards will now be sorted from 0 at front to 15 in back.